The present invention generally relates to a magnetic tape recording and reproducing apparatus and more particularly, to a cassette tape recorder capable of effecting reverse reproduction, i.e. reproduction of one side and the other side of a magnetic tape cassette without the necessity for turning over the tape cassette, and particularly the, employing a magnetic type cassette of a miniature type having first and second tape pads and first and second capstan holes formed at the outer opposite sides of said tape pads.
Conventionally, in a magnetic tape recording and reproducing apparatus or tape recorder capable of effecting reverse reproduction and having first and second capstans, it has been the general practice to change over the running or travelling direction of the magnetic tape in such a manner that a first pinch roller for running the magnetic tape in a first direction is brought into pressure contact with a first capstan, while a second pinch roller for running the magnetic tape in a second direction is brought into pressure contact with a second capstan, with pressure contact by the first and second pinch rollers with respect to the magnetic tape being alternately effected according to the change-over in the running direction of the tape.
The known arrangement as described above, however, has the disadvantages in that, although the second or first pinch roller not concerned with the tape running function during the running in the first or second direction is spaced from the second or first capstan, a pressure contact load is normally applied so as to be received at all times by an actuating means for actuating said first and second pinch rollers from a stationary state to a tape running state. More specifically, a load which is the sum of the pressure contact loads for the first and second pinch rollers is always applied to said actuating means during the tape running state, with a large driving force and a retaining force being required therefor, and accordingly, not only is a large operating force needed, but also high power is required if a driving means such as a solenoid or the like is employed as a consequence, the size of the apparatus is increased, thus presenting a considerable hindrance in the manufacture of a miniature tape recorder employing a miniature tape cassette and further demands in size reduction.
Meanwhile, in a tape recorder utilizing an ordinary or compact tape cassette somewhat larger in size than the miniature tape cassette, and capable of effecting a reverse reproduction, it is so arranged that the tape pad is provided at a central portion between two reel hubs, and consequently, there is provided only one magnetic head arranged to be applied both to the first tape running direction and the second tape running direction. The conventional arrangement as described above has such problems that, since it is difficult to bring the magnetic tape into exactly the same running state in the first running direction and in the second running direction, there may be a case where, if an azimuth of the magnetic head is adjusted during the running in the first direction, the azimuth of the magnetic head is undesirably deviated during the running in the second direction.
However, in the miniature tape cassette, since two tape pads, i.e. the first and second tape pads are provided, if first and second magnetic heads are provided to correspond to said first and second pads so as to use the first magnetic head during running in the first direction, and to utilize the second magnetic head during running in the second direction, the magnetic heads may be arranged to function at an optimum azimuth for both of the running directions. In the above case, however, there is the inconvenience that, if both the first and second magnetic heads are adapted to sufficiently contact the magnetic tape to a "deep" degree, the running load for the tape is undesirably increased, thus requiring a large force for driving the magnetic tape, with a resulting increase in the rotating load for the driving motor and an increase in power consumption.
Moreover, in the miniature tape recorder, for the stabilization of the running of the magnetic tape and also, for stabilization in contact between the magnetic heads and the magnetic tape, it is arranged to apply a back tension, and in the conventional arrangement, the application of such a back tension is effected by imparting a rotating load to a supply side reel base. However, the known practice as described above also gives rise to a load during fast forwarding and rewinding of the magnetic tape, thus requiring a large torque, with an increase in power consumption. Furthermore, when a tape position detecting function is effected by causing the magnetic tape to run at high speed, with the first and second magnetic heads contacting the magnetic tape, from the running state of the magnetic tape in the first and second directions as described earlier, the tape running load is still large, even if said first and second magnetic heads are arranged to slightly contact the magnetic tape by a "shallow" degree, also resulting in such drawbacks as a required large torque, increased power consumption of the driving motor, and a short life of the magnetic heads, etc.